Communications standards may employ a phase encoding technique sometimes referred to as Manchester encoding. Manchester encoding is characterized by a line code in which the encoding of each individual data bit 1) always has a transition at its midpoint and 2) occupies a consistent time period from bit to bit. As a transition is ensured at least once every bit, the receiving device may easily recover clock and data. Manchester encoding has no direct current (DC) component and thus may be coupled inductively or capacitively. A typical application may require a Manchester data encoder for data transmission and a receiver on the other end for decoding the encoded transmission.
The information carried by Manchester encoded data may be indicated by the midpoint transition (low-to-high, or high-to-low). An encoded data bit may include a transition at the start of a period, but this transition does not carry data. The interpretation of the midpoint transition is not universally consistent. According to a first convention established by G. E. Thomas (which will subsequently be observed herein), a low-to high transition (also expressed as “01”) may be interpreted as a logical zero (0) and a high-to-low transition (e.g., “10”) may be interpreted as a logical one (1). The alternative IEEE 802.3 convention reverses this interpretation: the low-to-high transition 01 is interpreted as a logical 1 and the high-to-low transition 10 as a logical 0.
One exemplary communications standard may employ Manchester encoded data (MED) in the transmission of data from point to point. Automated dependent surveillance broadcast (ADS-B) signals may be one awareness tool usable by pilots as well as air traffic control (ATC) and ground personnel for each to maintain positional awareness of, and separation assurance from, the other. ADS-B Out provides ATC facilities and nearby aircraft with real-time position information. ADS-B In refers to an appropriately equipped aircraft's ability to receive and display another aircraft's ADS-B Out information as well as additional ADS-B In services provided by ground systems and ATC facilities, including Automatic Dependent Surveillance-Rebroadcast (ADS-R), Traffic Information Service-Broadcast (TIS-B), and, if so equipped, Flight Information Service-Broadcast (FIS-B).
One example of ADS-B Out may include transmission/reception via Extended Squitter (ES) at a frequency of 1090 MHz (1090ES) using Manchester encoding for data transmission. However, correlating a plurality of received Manchester encoded 1090ES signals may pose a challenge for operators. Therefore, a need remains for a system and related method capable of efficiently decoding a plurality of received signals of noisy MED and accurately correlating the data stream to the intended resultant data set.